Checking if output of a command contains a certain string in a shell script

Question

I\'m writing a shell script, and I\'m trying to check if the output of a command contains a certain string. I\'m thinking I probably have to use grep, but I\'m not sure how.

Answer 1

Test the return value of grep:

./somecommand | grep 'string' &> /dev/null
if [ $? == 0 ]; then
   echo "matched"
fi

which is done idiomatically like so:

if ./somecommand | grep -q 'string'; then
   echo "matched"
fi

and also:

./somecommand | grep -q 'string' && echo 'matched'